A known passenger weight measuring instrument apparatus for determining a seat occupancy is disclosed in, for example, JP4267836B. According to the apparatus for determining the seat occupancy, load sensors are arranged between a cushion portion of a vehicle seat and a vehicle floor. The apparatus for determining the seat occupancy determines an occupancy of the vehicle seat on the basis of a sum of the loads, detected by the load sensors, in order to control a deployment of an air-bag and to control an operation of a seatbelt pretentioner.
The load sensors are respectively provided at four corners of a lower portion of the cushion portion of the vehicle seat via brackets. The load sensors detect loads, applied on the four corners of the cushion portion of the vehicle seat. Further, a seat occupancy determining portion compares the sum of the loads, detected by the load sensors, with a predetermined threshold value, thereby determining the occupancy of the vehicle seat by a passenger.
The occupancy of the vehicle seat, which is determined by the apparatus for determining the seat occupancy, is used to control an operation of an air-bag. More specifically, in a case where it is determined that an adult is seated on a front passenger seat of the vehicle, the air-bag is controlled so as to be fully deployable. On the other hand, in a case where it is determined that a passenger is not seated on the vehicle seat or that a child is seated on a child seat, being fixed to the vehicle seat, the air-bag is controlled so as not to be deployable.
In a case where there is a minor collision of the vehicle, an impact is applied on the vehicle. The impact may cause an application of a load, whose value is equal to or lager than a predetermined value, on the vehicle seat, on which a passenger is seated. Consequently, a seat frame may be slightly deformed. In a case where the load sensor is attached to the deformed portion of the seat frame, a position of a zero point (i.e., a position where the detected load is determined to be zero) of a detection system of the load sensor may be displaced. Accordingly, a subsequent detection of the seat occupancy load, applied on the vehicle seat, may not be accurately executed.
When a user of a vehicle assumes a collision of a vehicle to be minor, the user may choose not to have the vehicle inspected and repaired. In such case, the user may be unaware of a reduced accuracy in detecting the seat occupancy load and an inaccurate determination of the seat occupancy of the vehicle seat. Alternatively, an acceleration sensor may be provided to a vehicle, and a user may be informed of an application of an impact on the vehicle on the basis of an acceleration, detected by the acceleration sensor. However, in such a case, the acceleration sensor, a signal processing circuit and the like may be required to be additionally provided to the vehicle. Accordingly, a manufacturing cost of the vehicle may be increased.
A need thus exists for apparatus and method for determining an impact on a vehicle and an apparatus for warning an impact on a vehicle, which is not susceptible to the drawback mentioned above.